1. Field of the Invention
The present invention relates to an image detector having an active matrix substrate with multitudes of switching elements disposed thereon.
2. Description of the Related Art
Recently, a flat panel detector (FPD) has been put into practical use. The FPD includes an active matrix substrate with multitudes of switching elements disposed thereon and an X-ray sensitive layer stacked thereon, and is capable of directly converting X-ray information to digital data. The FPD is advantageous over a conventional imaging plate in that it allows for confirmation of a motion picture, as well as instantaneous confirmation of images.
As one of such FPDs, for example, Japanese Patent No. 3737343 proposes an image detector like that shown in FIG. 17.
The image detector proposed in Japanese Patent No. 3737343 includes a TFT array substrate 100 with multitudes of TFT switches disposed two-dimensionally, a semiconductor layer 116 which generates charges according to an electromagnetic wave incident thereon and is stacked on the TFT array substrate 100 such that the charges are read out by the TFT array substrate 100, an upper electrode 117 stacked on the semiconductor layer 116, and a protection substrate 118 stacked over the semiconductor layer 116 and upper electrode 117 so as to cover them, and a resin material 119 is filled in a space between the semiconductor layer 116/upper electrode 117 and protection substrate 118, as illustrated in FIG. 17.
When image detection is performed using the image detector described in Japanese Patent No. 3737343, a high voltage is applied to the upper electrode 117. This causes creeping discharges to occur from the upper electrode 117 to the wires of the TFT array substrate 100 through the surface of the semiconductor layer 116 which may possibly lead to wire breakages. But, as shown in FIG. 17, the wire breakages may be prevented by covering end portions of the semiconductor layer 116 with the resin material 119.
Where the bonding strength between the resin material 119 and TFT array substrate 100 in the image detector of Japanese Patent No. 3737343 is insufficient, however, a detachment problem arises at the interface between the resin material and TFT array substrate 100 by linear expansion due to temperature change, which will lead to creeping discharges or wire breakages.
Further, in the image detector of Japanese Patent No. 3737343, if detachment occurs between the resin material 119 and TFT array substrate 100, the protection substrate 118 is bonded to the TFT array substrate 100 only with contact surfaces thereof, which may also lead to the detachment of the protection substrate 118 due to lack of the bonding strength.
Generally, it is necessary to provide an organic insulating layer made of an organic material with a thickness of 1 to 2 μm on the TFT array substrate under the charge collection electrodes of the TFT array substrate in order to flatten the deposition surface of the TFT array substrate.
It has been found that, where the uppermost surface of the TFT array substrate is formed of an organic insulating material, the bonding strength between the resin material and organic insulating material is weak, and a detachment problem will eventually arise at the interface between the resin material and TFT array substrate 100 by linear expansion due to temperature change, which will then lead to creeping discharges or wire breakages.
In view of the circumstances described above, it is an object of the present invention to provide an image detector capable of preventing detachment of the resin material from the active matrix substrate.